Fluid dampening side bearings

ABSTRACT

The fluid side bearing, mounted on each side of the bolster of the truck, includes a pair of concentric elastomer rings surrounding a pair of interior hydraulic chambers connected by a regulating valve. The concentric rings coact with one another in stages and with the hydraulic system to dampen rocking motions of the car body relative to the truck bolster.

United States Patent 1 1 1111 3,730,104

Hood, II 1 1 May 1, i973 1 1 FLUID DAMPENING SIDE BEARINGS FOREIGN PATENTS OR APPLICATIONS Inventor: Charles "0011,11, Unicago- 574,817 l/l946 Great Britain ..105/200 A ig Amsted Industries lncarporated, 620,144 3/1949 Great Britain ..267/|4I Chicago, Ill. Primary Examiner-Gerald M. Forlenza [22] Flledz Apr. 9, 1971 Assistant Examinerl-loward Beltran 21 APPL 132 743 Att0rneyWalter L. Schlegel, Jr. and Russell W. Pyle 7 ABS [52] US. Cl. ..l05/l99 CB, 267/3, 267/118, [5 1 TRACT 3053/1355 The fluid side bearing, mounted on each side of the [51] Int. Cl. ..B61f 5/06, B61f 5/14, F160 17/04 bolster of the truck, includes a pair of concentric [58] Field of Search 105/197 B, 199 CB, elastomer rings surrounding a pair of interior hydrau- 105/200; 267/141, 3, 118; 308/137, 138 lic chambers connected by a regulating valve. The concentric rings coact with one another in stages and [56] References Cited with the hydraulic system to dampen rocking motions of the car body relative to the truck bolster. UNITED STATES PATENTS 3,626,864 12 1971 Wiebe ..105 200 6 3 Drawmg F'gures Patented May 1, 1973 2 Sheets-Sheet 1 gus adj Patented May 1, 1973 3,730,104

2 Sheets-Sheet 2 FLUID DAMPENING SIDE BEARINGS This invention relates to railway vehicles with means to control car rocking and more particularly to a combination elastomer-hydraulic snubber mounted on both sides of a truck bolster as a replacement for a conventional side bearing.

Of the various devices proposed to minimize car rocking, most require some structural modification to the truck or to the car body, or to both. Because of the standards established for the design of railway equipment, space limitations often become critical in the installation of a snubbing device having sufficient capacity to control car rocking. Although hydraulic devices have been used successfully to control car rocking, wear on movable seals normally found in such devices may cause maintenance problems.

Accordingly, an object of this invention is to provide a means to control car rocking that may be installed without structural modification to conventional railway equipment.

Another object is to provide a compact damping device including elastomer and hydraulic components, wherein the hydraulic component does not employ movable hydraulic seals.

Other objects will become apparent from the following description and appended claims, taken in connection with the accompanying drawing, wherein:

FIG. 1 is a transverse sectional view of a railway vehicle, showing the bolster of the truck in elevation and the rock control side bearing mounted thereon;

FIG. 2 is an isolated half sectional view of one of the rock control side bearings illustrated in FIG. 1; and

FIG. 3 is a detailed sectional view of the hydraulic valve assembly partly illustrated in FIG. 2.

With more particular reference to the drawing, which shows a preferred embodiment of the invention, FIG. 1 illustrates a railway vehicle comprising a car body supported upon a truck 12. The car body comprises spaced longitudinal side sills l4 and 16 and'a longitudinal center sill 18, all of which are connected by a transverse bolster 20. A male center plate 22 depends from the body bolster 20 and rests within the female center plate 24 of the underlying truck bolster 26, said truck and body bolsters being otherwise spaced from one another. The truck 12 comprises a pair of spaced side frames 28 and 30 with the bolster 26 resiliently supported therebetween on spring groups 32 within the side frames. The side frames 28 and 30 are supported upon wheel and axle assemblies, such as 34, with the wheels traveling on rails 36.

A pair of rock control side bearings 38 and 40 are located in a spaced relationship on the top of the truck bolster 26 and are in continuous engagement with respective pads 42 and 44 secured to the underside of the car bolster 20. The devices 38 and 40 are intended as a direct replacement for, and occupy approximately the same space as, a conventional side bearing.

As shown in FIG. 2, each of the rock control side bearings includes a base 46 secured to a bottom plate 48 by bolts 50, with the bottom plate being secured to the bolster 26 by means of flat top rivets, or the like. An upward tapered steel ring 52 is secured to the base 46 using a gasket or other oil type seal. Ring 52 separates inner and outer concentric elastomer rings 54 and 56, respectively, which are bonded to the ring and fomi a seal at the base. The outer elastomer ring 56 is bonded on its outer surface to an outer rigid ring 58, with the bottom of the ring being spaced from the base 46 and the top of the ring being located above the top of the tapered steel ring 52. The inner elastomer 54 is bonded at its inner surface to a liner 60, which is in turn sealed and secured by cap screws 62 or the like between a clamp ring 64 and a gasket 66 to the bottom of a downwardly tapered hollow cup 68. A cap is secured and sealed to the top of the cup 68 and is of a diameter large enough to be engageable with the top of the outer rigid ring 58, but is normally spaced therefrom. The bottom of the cup 68 is spaced from the base 46. The distance from the base 46 to the cap 70 is such as to allow the cap to be in constant contact with the pads 42 and 44 of the car bolster 20. It may be seen that the outer elastomer ring slopes upward from the entire height of the tapered steel ring to substantially the entire height of the outer rigid ring 58, and the inner elastomer 54 slopes upward from the entire height of said steel ring to substantially the entire height of the cup 68.

As shown in FIG. 2, the cap 70 and its depending cup 68 define an upper sealed chamber 72, and the inner elastomer 54, cup and base 46 define a lower sealed chamber 74. As shown in FIGS. 2 and 3, a circular opening is provided in the center of the bottom of the cup 68, and a two-way valve means 76 is secured therein by means of flange 78 extending from the valve means to a groove 80 in the cup bottom above the gasket 66. Hydraulic fluid (not shown) is provided in the lower chamber 74 and a portion of the upper chamber 72. The valve means is designed in such a manner that flow of hydraulic fluid is restricted or metered from the lower to upper chamber upon compression of the rock control side bearing and unrestricted in the reverse direction upon extension of the side bearing. In order to achieve these characteristics, the valve means comprises a metering valve operative upon compression, and a dump valve operative upon extension.

The valve means comprises a base 82 having a large, outwardly flared, bottom opening 84, and a cylindrical sleeve 86 above the base connected thereto by a plurality of straps 88 having ports therebetween. A cylindrical member 90 is slidably received within the sleeve 86, extends above the sleeve, and is secured at its lower end to a poppet valve 92, which covers or mates with the bottom opening 84 along the flared surface thereof. A plurality of ports 94 are provided in the base of the cylindrical member 90 adjacent to the poppet valve 92.

A compression piston 96 is slidably received in a lower portion of the cylindrical member 90 and engages a central circular aperture 98 in the poppet valve 92. The piston 96 has an upper shoulder 100 engageable with a shoulder on the cylindrical member 90 to limit downward movement of the piston. A helical spring 102 extends between a spring seat 104 on the top of the piston 96 and a spring guide 106 retained within the cylindrical member 90 by a snap ring 108. A second helical spring 1 10 extends around the sleeve 86 from the valve base 82 to the cylindrical member 90 and is retained by respective upper and lower washers 1 l2 and 114 held by respective snap rings 1 l6 and 118. A splash guard or shroud having a downwardly depending flange is secured around the sleeve 86 above the straps 88 to prevent entrainment of air with hydraulic fluid entering the upper chamber. Other equivalent means, such as an elastic bag around the entry ports, or other forms of shrouding, could also be used for this purpose. Relief ports 122 are provided above the compression piston 96 between the sleeve 86 and the cylindrical member 90 and communicate with the ports between the straps 88 to drain off hydraulic fluid that may leak around the compression piston.

In operation, as shown in FIGS. 1-3, as the car body rocks on its center plate toward the bolster 26 of the truck 12, either one of the rock control side bearings is compressed. In the first stage of compression the cap 70 moves toward the base 46 against the resistance afforded by flexing of the inner elastomer 54, together with the dynamic resistance of the hydraulic fluid, the latter being a function of the pressure drop across the ports 91 times the effective area of the chamber 74. If the device is sufficiently compressed, the cap 70 will also engage the outer ring 58 which is attached to the outer elastomer 56, causing both elastomers to work in parallel. Under normal level conditions, the device is designed to be compressed only against the resistance of the inner elastomer.

The use of two elastomers acting successively in parallel offers several advantages over a system with a single elastomer. At the installed height, with the devices slightly compressed, a static force in each unit significantly in excess of 5,000 pounds would hinder proper swiveling of the car on the truck. On the other hand, experiments have shown that about 30,000 pounds of force should be exerted by the elastomer at maximum compression. Since the distance between the bolsters of the car and truck is limited, a selection of a single elastomer having the proper spring rate within the confines of the system would be difficult, if not impossible. A second elastomer provides the necessary force at maximum compression and may be designed to have a higher spring rate than the first elastomer.

Also during compression, hydraulic fluid is transferred from the lower chamber 74 to the upper chamber 72 through the valve 76. The hydraulic fluid forces the compression piston 96 upward against the resistance of the spring 102 untilfluid passes through the aperture 98 and through the ports 94 between the straps 88 into the upper chamber 72. The splash guard 120 prevents excess aeration of the hydraulic fluid. The work done by the fluid passing from the lower chamber to the upper chamber is dissipated as heat, thereby damping oscillation of the car body. A relief port 122 above the piston 96 between the cylindrical member 90 and the upper chamber 72 provides for the escape of fluid that may leak between said piston and said cylindrical member.

During extension, the elastomers 54 and 56 maintain the side bearing in intimate contact with the car body. They also provide some damping action in addition to that of the hydraulic system. At the same time, the force of the spring 102, being greater than the pressure in the lower chamber 74, causes the compression valve to close. Return of hydraulic fluid from the upper to lower chamber. is caused by air pressure acting on the hydraulic fluid, and such return is unrestricted by virtue of a one-way dump or poppet valve incorporated within the valve structure 76. Hydraulic pressure is exerted on the poppet 92, which has a large exposed surface area in comparison to the compression piston 96. Opening of the valve 92 is resisted by a weak spring 110, and the cylindrical member 90 moves downward relative to the sleeve 86, allowing for rapid and unrestricted return of hydraulic fluid to the lower chamber 74.

It may be seen that the inner elastomer 54 provides the necessary seal for the hydraulic portion and eliminates the need for moving seals. Another advantage is that the hydraulic valve may be designed such that the ratio of force to displacement is tailored to the needs of the system.

It may also be seen that the degree of taper of the ring 52, as well as the degree of taper of the liner and the ring 58, control the rate at which the elastomers 54 and 56 are compressed. It is therefore possible to vary the characteristics of the side bearing by changing the taper of one or more of the aforesaid parts.

Having thus described the invention, what is claimed is:

1. In a railway vehicle, a car bolster overlying and supported upon a truck bolster by means of bearing surfaces at their respective centers, a compressible side bearing having a first part secured to the truck bolster and a second part spaced from said first part and engaging the car bolster, a first elastomer ring secured between said first and second part, a second elastomer ring of larger diameter than the first ring and concentric therewith, and a rigid ring surrounding said second elastomer ring, said second elastomer ring being connected between said first part and said rigid ring and hydraulic means surrounded by said elastomer rings, said hydraulic means yieldingly resisting movement of said first and second parts toward one another and allowing substantially free movement of said parts away from one another.

2. The combination according to claim 1 wherein said rigid ring surrounding said second elastomer ring is dimensioned to engage said second part before said first elastomer ring attains maximum compression.

3. The combination according to claim 1 wherein said hydraulic means comprises a lower hydraulic chamber in said first part and an upper hydraulic chamber in said second part, hydraulic fluid in said lower chamber and a portion of said upper chamber, a one-way metering valve from said lower chamber to said upper chamber operative to restrict fluid flow thereto, and a one-way dump valve from said upper chamber to said lower chamber operative to allow substantially free flow of hydraulic fluid thereto.

4. The combination according to claim 3 wherein an elastomer ring is connected between said first and second parts and forms a seal for said lower hydraulic chamber.

5. In a railway vehicle including a truck having a pair of spaced side frames and a bolster resiliently supported between said side frames, and a car body having a bolster overlying and supported upon said truck bolster by means of engaging bearing surfaces at the respective centers thereof, said car bolster being otherwise spaced from said truck bolster, the improvement comprising a side bearing secured to the top of the truck bolster between the bearing surface thereof and each side frame, said side bearing comprising a lower part secured to said truck bolster and an upper part spaced from said lower part and engaging said body bolster, hydraulic means to yieldingly resist movement of said upper and lower parts toward one another and permitting substantially free movement of said parts away from each other, and a plurality of resilient members between said upper and lower parts and compressible upon movement of said parts toward one another, one of said resilient members being connected between said upper and lower parts, and another of said resilient members connected to said lower part and engageable with said upper part after partial compression of said one resilient member.

6. A rock control side bearing comprising a base, a rigid upwardly tapered ring secured to said base, a cap spaced from said base, a downwardly tapered cup depending from said base and secured and sealed thereto, said cup having an aperture centrally located therein,

the bottom of said cup being spaced from said base, a first elastomer ring connecting the side of said cup to said tapered ring, a rigid ring surrounding said tapered ring and spaced therefrom, said rigid ring being normally spaced from, but engageable with, said cap and said base, a second elastomer ring connecting said rigid ring to said tapered ring, an upper chamber formed by said cap and cup, a lower chamber formed by said cup, base and first elastomer ring, valve means between said upper and lower chambers secured within the aperture of said cup, and hydraulic fluid in said lower chamber and a portion of said upper chamber, said valve means yieldingly resisting flow of hydraulic fluid from said lower chamber to said upper chamber and allowing substantially free flow of hydraulic fluid from said upper chamber to said lower chamber.

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1. In a railway vehicle, a car bolster overlying and supported upon a truck bolster by means of bearing surfaces at their respective centers, a compressible side bearing having a first part secured to the truck bolster and a second part spaced from said first part and engaging the car bolster, a first elastomer ring secured between said first and second part, a second elastomer ring of larger diameter than the first ring and concentric therewith, and a rigid ring surrounding said second elastomer ring, said second elastomer ring being connected between said first part and said rigid ring and hydraulic means surrounded by said elastomer rings, said hydraulic means yieldingly resisting movement of said first and second parts toward one another and allowing substantially free movement of said parts away from one another.
 2. The combination according to claim 1 wherein said rigid ring surrounding said second elastomer ring is dimensioned to engage said second part before said first elastomer ring attains maximum compression.
 3. The combination according to claim 1 wherein said hydraulic means comprises a lower hydraulic chamber in said first part and an upper hydraulic chamber in said second part, hydraulic fluid in said lower chamber and a portion of said upper chamber, a one-way metering valve from said lower chamber to said upper chamber operative to restrict fluid flow thereto, and a one-way dump valve from said upper chamber to said lower chamber operative to allow substantially free flow of hydraulic fluid thereto.
 4. The combination according to claim 3 wherein an elastomer ring is connected between said first and second parts and forms a seal for said lower hydraulic chamber.
 5. In a railway vehicle including a truck having a pair of spaced side frames and a bolster resiliently supported between said side frames, and a car body having a bolster overlying and supported upon said truck bolster by means of engaging bearing surfaces at the respective centers thereof, said car bolster being otherwise spaced from said truck bolster, the improvement comprising a side bearing secured to the top of the truck bolster between the bearing surface thereof and each side frame, said side bearing comprising a lower part secured to said truck bolster and an upper part spaced from said lower part and engaging said body bolster, hydraulic means to yieldingly resist movement of said upper and lower parts toward one another and permitting substantially free movement of said parts away from each other, and a plurality of resilient members between said upper and lower parts and compressible upon movement of said parts toward one another, one of said resilient members being connected between said upper and lower parts, and another of said resilient members connected to said lower part and engageable with said upper part after partial compression of said one resilient member.
 6. A rock control side bearing comprising a base, a rigid upwardly tapered ring secured to said base, a cap spaced from said base, a downwardly tapered cup depending from said base and secured and sealed thereto, said cup having an aperture centrally located therein, the bottom of said cup being spaced from said base, a first elastomer ring connecting the side of said cup to said tapered ring, a rigid ring surrounding said tapered ring and spaced therefrom, said rigid ring being normally spaced from, but engageable with, said cap and said base, a second elastomer ring connecting said rigid ring to said tapered ring, an upper chamber formed by said cap and cup, a lower chamber formed by said cup, base and first elastomer ring, valve means between said upper and lower chambers secured within the aperture of said cup, and hydraulic fluid in said lower chamber and a portion of said upper chamber, said valve means yieldingly resisting flow of hydraulic fluid from said lower chamber to said upper chaMber and allowing substantially free flow of hydraulic fluid from said upper chamber to said lower chamber. 